Associated parameters of canine impaction in patients with unilateral cleft lip and palate after secondary alveolar bone grafting: a retrospective study

Associated parameters of canine impaction in patients with unilateral cleft lip and palate after... Summary Objectives To compare parameters related to impacted canines at the cleft versus the normal contralateral side and with non-impacted canines at the cleft side in unilateral cleft lip and palate (UCLP) patients. We also aim to search for possible associated parameters enabling prediction of canine impaction in these patients. Materials and methods Ninety-five non-syndromic UCLP patients were included and divided into group A (n = 41 patients) with unilateral impacted canines at the cleft side (A1) and spontaneously erupted canines at the non-cleft side (A2) and group B with spontaneously erupted canines at the cleft side (n = 54 patients). Clinical information and radiographic parameters on panoramic radiographs were collected and compared between groups using a generalized linear mixed model, a Mann–Whitney U-test, a Fisher’s exact test, and receiver operating characteristic tests. Results Impaction of the maxillary canine at the cleft side in UCLP patients can be suspected in case of delayed canine root development, a higher vertical position and sector score (P < 0.05) and higher angles between the canine and the midline, as well as between canine and lateral incisor and between first premolar (P < 0.001). Results clearly indicate that the erupting canine position at the cleft side, even when not impacted, is different from the non-cleft side. Conclusion There is a great risk for canine impaction at the cleft side in UCLP patients when the canine position is more apical than one-third of the root of the adjacent lateral incisor and when the angles between canine and midline and between canine and first premolar are higher than 23.82 and 16.1 degrees, respectively. These associated parameters should have to be studied in a prospective setting to confirm their predictive value. Introduction Non-syndromic oral clefts are the most common craniofacial anomaly. The incidence of unilateral cleft lip and palate (UCLP) has been reported to be 1.3 to 1.5/1000 in Belgium and the Netherlands (1). Genetic as well as environmental and local factors can contribute to the aetiology and pathogenesis of orofacial clefts (2). Dental abnormalities in number, size, and position are more commonly observed in cleft patients. More specifically, the prevalence of canine impaction in cleft patients is significantly higher compared with the general population, with a prevalence going up to 82 per cent in patients with UCLP (3–11), while in the general population, the frequency of occurrence ranges from 0.9 to 2.2 per cent (12–15). This difference in prevalence could be explained by the individual characteristics of the cleft, agenesis, and supernumerary teeth in the cleft region and the surgical procedures conducted in that area (1). In patients with UCLP, an alveolar bone graft is indispensable. The aim of this graft is to close the oronasal communication and to create a bony environment for the canine to erupt. The preferred moment to perform an alveolar bone graft is before maxillary canine eruption when the canine root development is one-fourth to a half (4). Ideally, the bone graft should be performed in combination with maxillary expansion before eruption of the canine to create a larger bony area and to decrease the impaction risk (7, 16–19). Up until now, iliac crest cancellous bone is still considered the ‘gold standard’ donor material (20). Canine impaction complicates the orthodontic treatment and may have deleterious effects on the adjacent teeth. Early diagnosis of canine impaction is crucial, and therefore, it is important to identify potentially predisposing factors. The aim of this study is to compare cleft-related impacted canine parameters with the normal contralateral side and with cleft-related non-impacted canine parameters in UCLP patients and to search for associated parameters of canine impaction at the cleft side that could possibly predict impaction. Materials and methods The Medical Ethics Committee of the University Hospitals Leuven registered and approved this study with the registration number S58229. Patient selection The present study sample consisted of non-syndromic UCLP patients who underwent secondary alveolar bone grafting between September 1997 and September 2016. All included patients were treated in the University Hospitals of Leuven, according to the same protocol, where lip closure is performed at the age of 3 months, the soft palate at approximately 12–18 months of age, and the hard palate at 4–6 years of age. The timing of the bone graft depends on the eruption of the canine and the position of the lateral incisor. It is most frequently performed around the age of 9, to allow eruption of the maxillary canine in a bony area. When the lateral incisor is located in the small segment, the bone graft is performed earlier. Two hundred and fifty-seven patients underwent secondary alveolar bone grafting between September 1997 and September 2016. Patients were excluded from the study when they had bilateral clefts (n = 60), unilateral cleft lip, and alveolus (n = 35), incomplete lip or palatal clefts (n = 13), clefts in the context of a syndrome (n = 9), when they were not surgically treated according to our protocol (n = 9), had their orthodontic treatment elsewhere (n = 5), when the maxillary canine was not erupted at the time of evaluation (n = 28), and when the patients had incomplete files (n = 3). The final sample consisted of 95 non-syndromic UCLP patients (65 males and 30 females, 31 cleft right side and 64 left side). The patients were divided into two groups according to their maxillary canine eruption. Group A included 41 patients with unilateral impacted canines at the cleft side (group A1) and spontaneously erupted canines at the non-cleft side (group A2). Group B included 54 patients with spontaneously erupted canines at both the cleft (group B) and non-cleft side (not used in the present study). Canines were considered as impacted according to the definition of Thilander and Jakobsson: ‘An impacted tooth is a tooth whose eruption is considerably delayed and for which there is clinical or radiographic evidence that further eruption may not take place’ (21). The canine needed to meet the following objective criteria to be classified as impacted and to be surgically exposed: the contralateral canine was erupted, the apex of the suspected canine was already closed, and the bone grafting procedure was performed more than 18 months ago. Data collection methods We collected the following parameters from the patient’s clinical records: gender, date of birth, date of secondary alveolar bone grafting, date of surgical exposure of the canine, presence of a crossbite, history of interceptive treatment, type of occlusion, and cleft side. Evaluation of radiographic parameters was performed on panoramic radiographs (OPG) before surgical exposure of the canine in group A and after the secondary bone graft where the root development of the canine was at least two-thirds in group B. The used parameters are explained in Table 1 and Figure 1. Table 1. Description of categorical and continuous variables. Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Canine development was scored according to the grading system of Ericson and Kurol (22); vertical position was scored using a modification on the method of Power and Short (23) (the central incisor was used when the lateral incisor was absent); for sector score, a modification on the method of Ericson and Kurol (22) was used (the central incisor was used when the lateral incisor was absent). View Large Table 1. Description of categorical and continuous variables. Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Canine development was scored according to the grading system of Ericson and Kurol (22); vertical position was scored using a modification on the method of Power and Short (23) (the central incisor was used when the lateral incisor was absent); for sector score, a modification on the method of Ericson and Kurol (22) was used (the central incisor was used when the lateral incisor was absent). View Large Figure 1. View largeDownload slide OPGs illustrating (a) vertical position of the canine (23), (b) sector of the canine (22), (c) angular measurements with (A) angle of maxillary canine to midline (= line through the inter-incisal point, perpendicular on the bottom of the OPG), (B) angle of maxillary canine to lateral incisor (the central incisor was used when the lateral incisor was absent), and (C) angle of maxillary canine to first premolar. Figure 1. View largeDownload slide OPGs illustrating (a) vertical position of the canine (23), (b) sector of the canine (22), (c) angular measurements with (A) angle of maxillary canine to midline (= line through the inter-incisal point, perpendicular on the bottom of the OPG), (B) angle of maxillary canine to lateral incisor (the central incisor was used when the lateral incisor was absent), and (C) angle of maxillary canine to first premolar. The OPGs were generated by a Siemens Orthopantomograph (Sirona Dental, Bensheim, Germany), a Cranex Tome (Soredex, Tuusula, Finland), a Veraviewpocs 2D (J. Morita Co., Kyoto, Japan), a VistaPano (Dürr Dental, Bietigheim-Bissingen, Germany), or a Promax 2D (Planmeca Inc., Helsinki, Finland). Statistical analysis Comparisons between group A1 and A2 were obtained by means of a generalized linear mixed model for binomial responses with a logit link and patient as a random factor. Comparisons between group A1 and B were obtained by means of a generalized linear model for binomial responses with a logit link. Model coefficients and their variance–covariance matrix were used to calculate the differences between the two groups. Continuous variables were compared between group A1 and B using a Mann–Whitney U-test. Non-continuous variables were compared between the same groups using a Fisher’s exact test. Receiver operating characteristic (ROC) curves were calculated to create threshold values for canine impaction (group A1 versus group B). For 20 randomly selected patients, the measurements were repeated after 1 month by the same observer and by a second observer. Rater agreements for categorical variables were assessed by means of a Fleiss’s Kappa statistic and for continuous variables by means of an intra-class correlation coefficient (ICC). P-values were only rated significant if they were smaller than 0.05. Results The descriptive data of the sample have been summarized in Table 2. Table 2. Descriptive data of the study sample. Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 View Large Table 2. Descriptive data of the study sample. Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 View Large Comparison of the impacted canine at the cleft side (A1) versus the spontaneously erupted canine at the non-cleft side (A2) In group A1, the patients had significantly more Class II malocclusion (P = 0.0043), while in group A2, they had significantly more Class III malocclusion (P = 0.0318). The canines at the non-cleft side were more developed than at the cleft side. The lateral incisor was often missing (41.5 per cent) or abnormal (46.3 per cent) at the cleft side. The vertical position of the maxillary canine was significantly higher at the cleft side versus the non-cleft side. At the non-cleft side, the canine was significantly more in the line of the arch in comparison with the cleft side. The canines at the non-cleft side had significantly more a sector score of 0. There was a significant difference between the angulations at both sides (P = 0.0001). The mean angle between the canine and the midline was 35.56 degrees at the cleft side and 5.34 degrees at the non-cleft side. The mean angle between the canine and the lateral incisor was 46.21 degrees at the cleft side and 7.93 degrees at the non-cleft side. The mean angle between the canine and the first premolar was 29.5 degrees at the cleft side and 5.91 degrees at the non-cleft side (Table 3 and Figure 2). Table 3. Comparison of categorical and continuous variables between groups A1, A2, and B (*P ≤ 0.05). Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* View Large Table 3. Comparison of categorical and continuous variables between groups A1, A2, and B (*P ≤ 0.05). Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* View Large Figure 2. View largeDownload slide Boxplots showing the difference in canine angulation with respect to (a) midline, (b) lateral incisor, and (c) first premolar between groups A1, A2, and B. Figure 2. View largeDownload slide Boxplots showing the difference in canine angulation with respect to (a) midline, (b) lateral incisor, and (c) first premolar between groups A1, A2, and B. Comparison cleft side with impaction (A1) versus cleft side without impaction (B) There were no significant differences in occlusion and in development of the canine between both groups. The lateral incisor was often missing or abnormal in both groups; no significant difference was noted. The vertical position of the maxillary canine was significantly higher in group A1 versus group B. In group B, the canine was significantly more in the line of the arch in comparison with group A1 (P = 0.007), where the canine was significantly more palatally located. The canines in group B had significantly more a sector score of 0. There was a significant difference between the three angles in group A1 versus group B (P = 0.0001). The mean angle between the canine and the midline was 35.56 degrees in group A1, while it was 18.92 degrees in group B. The mean angle between the canine and the lateral incisor was 46.21 degrees in group A1 and 28.39 degrees in group B. The mean angle between the canine and the first premolar was 29.5 degrees in group A1 and 13.14 degrees in group B (Table 3 and Figure 2). Impaction of the maxillary canine at the cleft side in UCLP patients can be suspected in case of delayed canine root development, a higher vertical position and sector score (P < 0.05) and higher angles between the canine and the midline, as well as between canine and lateral incisor and between first premolar (P < 0.001). It must be noted that the position of an erupting canine at the cleft side, even when not impacted, is different from the non-cleft side. The three angles are significantly larger, root development and eruption are slower, and canines have a more mesial position than those at the non-cleft side. ROC tests were performed to decide which continuous and ordinal parameters were the best-associated parameters of canine impaction at the cleft side. According to our measurements, the angulation between the canine and the midline was the best parameter, followed by the angulation between the canine and the first premolar, the vertical position of the canine, the angulation between the canine and the lateral incisor and the sector score. The area under the curve (AUC) for canine development was too low to have a clinically significant predictive value. Based on the aforementioned parameters, certain cut-off values were set to discriminate between impaction and non-impaction of the canine at the cleft side (Table 4). Table 4. Discrimination between impaction and non-impaction at the cleft side (A1 versus B). Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Angles are shown in degrees, vertical position, and sector score are shown as mentioned in Table 2. View Large Table 4. Discrimination between impaction and non-impaction at the cleft side (A1 versus B). Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Angles are shown in degrees, vertical position, and sector score are shown as mentioned in Table 2. View Large The Fleiss’s kappa value for the inter-observer agreement ranged from 0.60 to 0.94, except for resorption of the lateral incisor, for which it was 0.46. The Fleiss’s kappa value for the intra-observer agreement ranged from 0.75 to 1. The ICC was 0.95 or higher for both inter-observer and intra-observer agreement. Discussion Maxillary canine impaction is an important clinical manifestation, as it is frequently found in UCLP patients. In spite of this, it remains to be an understudied clinical feature. Early diagnosis of canine impaction is crucial to prevent resorption of adjacent teeth, and therefore, it would be valuable to identify potentially predisposing factors. There have been several attempts to predict canine impaction on OPGs in the general population, but in patients with UCLP, evidence is still lacking (24–28). In our sample, the patients in group A were significantly older than those in group B (12.67 years versus 11.58 years). As a consequence, the canines in group B should be less developed, should have a higher vertical position, and larger angles with the midline, lateral incisor, and first premolar. However, according to our results, there is no significant difference in canine development between group A and B, despite the fact that the patients in group B were significantly younger at the time of the OPG. As a consequence, if the patients in group B would have the same age as in group A, the differences would be even greater. El Deeb et al. (4) indicated that canines at the cleft side erupt slower than those at the contralateral side, and additionally, delayed root development may increase the risk of tooth impaction. Our results are consistent with these findings. Canines at the cleft side had a higher vertical position in comparison with canines at the non-cleft side, and impacted canines had a slower root development than spontaneously erupted canines. As mentioned in the Results section, patients with an impacted canine at the cleft side had significantly more often a Class II malocclusion than the same patients at the non-cleft side. This fact may be due to mesialization of the teeth at the cleft side, as a consequence of an absent or abnormal lateral incisor. Several authors state that impaction often coincides with an absent or abnormal lateral incisor (9, 19, 29), as the guidance theory indicates that the lateral incisor plays a significant role in guiding the maxillary canine to its correct position. Contradictory, other authors have found that lateral incisor agenesis does not modify the impaction risk (8, 30–32). In the present study, when group A1 (impacted canine at the cleft side) was compared with group B (spontaneously erupted canine at the cleft side), no significant differences between both groups were found for the presence of the lateral incisor. According to our findings, an absent or abnormal lateral incisor is more a characteristic of a cleft site than a predictor for impaction, which would support the idea that lateral incisor agenesis does not modify the impaction risk, as stated by the most recent literature (8, 32). Several authors have already suggested that certain parameters could be distinctive for canine impaction. Therefore, ROC tests were performed on the study variables to determine the best-associated parameters of canine impaction in patients with UCLP. First, the angle between the canine and the midline could have a predictive value for tooth impaction. Russel and McLeod stated that an angle greater than 45 degrees indicated risk of canine impaction (19), while Westerlund et al. (11) set the cut-off for this at an angle larger than 30 degrees and Ericson and Kurol (22) at an angle larger than 25 degrees. Nevertheless, in patients with UCLP, the mean angle between the maxillary canine and the midline at the cleft side is already significantly larger than at the non-cleft side, even when the canine is not impacted. Therefore, only the parameters of the canines at the cleft sides (group A1 versus group B) were compared to determine the cut-off values because the measured angles are not comparable with non-cleft sides. Based on this, the mean angle between the impacted canine and the midline was 35.56 degrees, and a cut-off value of 23.8 degrees was set in the present study. Warford et al. (28) stated that sector score is the most important predictor of eventual impaction. They also stated that angulation does not play a significant role in prediction of canine impaction. Ericson and Kurol (22) and Sajnani and King (27), on the contrary, describe angulation of the canine to the midline as a powerful prediction factor, as well as the angulation of the canine to the lateral incisor and the sector score. Alqerban et al. (25) found the angle between the canine and the first premolar to be a good discriminator for canine impaction. In the present study, statistically significant differences were noticed between the impacted canines and both control groups for the above-mentioned study variables, supporting the idea that these parameters are indeed good discriminators for impaction. However, the sector score and the angle between the canine and the lateral incisor may not be the most appropriate discriminators for canine impaction in patients with UCLP because the lateral incisor is often absent or abnormal, and other parameters should, in our opinion, be preferred. The ROC tests have indicated that the angle between the canine and the midline, the angle between the canine and the first premolar, and the vertical position of the canine are the three best-associated parameters of canine impaction with the cut-off values mentioned in Table 4. It is important to state that our estimation of the cut-off values was based on one OPG per patient, so they are most valid when the patients are around the age of 11–13 years old. The male:female ratio in patients with UCLP is 2:1, and the left side is significantly more affected than the right side (1, 33). The present study population follows this distribution. In the general population, girls also have twice as often impacted canines (34). However, we can’t make statements about the correlation gender and impaction in the present study population because of the size of the groups (Table 2). Most of our measurements were performed on OPGs. Although limitations of 2D images have been widely discussed in literature (distortion, magnification, superimposition, and positioning errors) (35), they remain to be of great clinical value because they are routinely taken at multiple moments throughout the patient’s treatment. Three-dimensional radiographs are exempt of this problem, but in CLP patients, they are already taken before and after the bone graft. Due to this, it not always justified to take an additional 3D radiograph only for canine impaction screening, with the extra radiation dose and costs that this implies. Additionally, several authors indicate that angular and linear measurements can be accurately performed on OPGs (25, 27, 35). In the present study, the kappa values and the ICC were acceptable, except for resorption of the lateral incisor, which showed a kappa value of 0.46. This implies that resorption is not consistently measurable on OPGs. To know the exact position of the canine and to evaluate the exact amount of resorption of the adjacent teeth, 3D images remain to be the ideal radiographic projection. It is important to notice that the present study has some limitations regarding the study design. It is a retrospective cross-sectional study which means that it has less power than a prospective study to support the outcomes mentioned in the Results section. Ideally, the associated parameters of canine impaction should be studied in a prospective setting to confirm their predictive value. Additionally, a split-mouth design was used in the present study, which may not be the best option in patients with UCLP because of the aforementioned genetic, environmental, and local factors. Two control groups were used: one where the impacted canine at the cleft side (group A1) was compared with a non-impacted canine at the non-cleft side (group A2) and another UCLP control group where the non-impacted canine at the cleft side (group B) was used. Ideally, non-cleft patients without tooth impaction should be used as a control group. As it often happens with comparative studies regarding conditions with low prevalence as cleft lip and palate, the groups included a small number of patients, and a cross-sectional retrospective design had to be used. Prospective longitudinal multicenter studies with large sample sizes and good control groups should be encouraged to validate the predictive value of the parameters found in the present study and to draw further conclusions. Despite these limitations, determining associated parameters of canine impaction in UCLP patients still has a clear clinical value. Up until now, the decision to intervene the maxillary canine eruption in these patients has been most frequently based on subjective factors. In the present study, cut-off values for several parameters with an adequate AUC were statistically determined, in order to be able to distinguish between impaction and non-impaction at the cleft side. This contrasts other articles studying patients with cleft lip and palate taking only one distinctive parameter into account or with non-statistically supported cut-off values (11, 19). We believe that our parameters can help the practitioner to make a more objective and scientifically based decision and can pave the way for further research. However, these parameters remain to be a diagnostic tool, and each patient should be evaluated on an individual level. Conclusion Careful follow-up of maxillary canines is crucial in patients with UCLP. OPGs are useful to evaluate the eruption path of the maxillary canines, while root resorption and canine position are ideally evaluated in 3D images. In the present study, the three best-associated parameters of canine impaction at the cleft side are a vertical position more apical than one-third of the root of the lateral incisor and the angles between canine and midline and between canine and first premolar larger than 23.82 and 16.1 degrees, respectively. These parameters represent a valuable tool to help the practitioner in their decision to intervene when they suspect an impacted canine in UCLP patients. However, they should be studied in a prospective setting to confirm their predictive value. Conflict of Interest None to declare. References 1. Dewinter , G. , Quirynen , M. , Heidbüchel , K. , Verdonck , A. , Willems , G. and Carels , C . 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Google Scholar CrossRef Search ADS PubMed 28. Warford , J.H. , Jr , Grandhi , R.K. and Tira , D.E . ( 2003 ) Prediction of maxillary canine impaction using sectors and angular measurement . American Journal of Orthodontics and Dentofacial Orthopedics , 124 , 651 – 655 . Google Scholar CrossRef Search ADS PubMed 29. Vichi , M. and Franchi , L . ( 1996 ) Eruption anomalies of the maxillary permanent cuspids in children with cleft lip and/or palate . The Journal of Clinical Pediatric Dentistry , 20 , 149 – 153 . Google Scholar PubMed 30. Tortora , C. , Meazzini , M.C. , Garattini , G. and Brusati , R . ( 2008 ) Prevalence of abnormalities in dental structure, position, and eruption pattern in a population of unilateral and bilateral cleft lip and palate patients . The Cleft Palate-Craniofacial Journal , 45 , 154 – 162 . Google Scholar CrossRef Search ADS PubMed 31. Oberoi , S. , Gill , P. , Chigurupati , R. , Hoffman , W.Y. , Hatcher , D.C. and Vargervik , K . 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The Angle Orthodontist , 77 , 430 – 435 . Google Scholar CrossRef Search ADS PubMed 35. Stramotas , S. , Geenty , J.P. , Darendeliler , M.A. , Byloff , F. , Berger , J. and Petocz , P . ( 2000 ) The reliability of crown-root ratio, linear and angular measurements on panoramic radiographs . Clinical Orthodontics and Research , 3 , 182 – 191 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The European Journal of Orthodontics Oxford University Press

Associated parameters of canine impaction in patients with unilateral cleft lip and palate after secondary alveolar bone grafting: a retrospective study

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Abstract

Summary Objectives To compare parameters related to impacted canines at the cleft versus the normal contralateral side and with non-impacted canines at the cleft side in unilateral cleft lip and palate (UCLP) patients. We also aim to search for possible associated parameters enabling prediction of canine impaction in these patients. Materials and methods Ninety-five non-syndromic UCLP patients were included and divided into group A (n = 41 patients) with unilateral impacted canines at the cleft side (A1) and spontaneously erupted canines at the non-cleft side (A2) and group B with spontaneously erupted canines at the cleft side (n = 54 patients). Clinical information and radiographic parameters on panoramic radiographs were collected and compared between groups using a generalized linear mixed model, a Mann–Whitney U-test, a Fisher’s exact test, and receiver operating characteristic tests. Results Impaction of the maxillary canine at the cleft side in UCLP patients can be suspected in case of delayed canine root development, a higher vertical position and sector score (P < 0.05) and higher angles between the canine and the midline, as well as between canine and lateral incisor and between first premolar (P < 0.001). Results clearly indicate that the erupting canine position at the cleft side, even when not impacted, is different from the non-cleft side. Conclusion There is a great risk for canine impaction at the cleft side in UCLP patients when the canine position is more apical than one-third of the root of the adjacent lateral incisor and when the angles between canine and midline and between canine and first premolar are higher than 23.82 and 16.1 degrees, respectively. These associated parameters should have to be studied in a prospective setting to confirm their predictive value. Introduction Non-syndromic oral clefts are the most common craniofacial anomaly. The incidence of unilateral cleft lip and palate (UCLP) has been reported to be 1.3 to 1.5/1000 in Belgium and the Netherlands (1). Genetic as well as environmental and local factors can contribute to the aetiology and pathogenesis of orofacial clefts (2). Dental abnormalities in number, size, and position are more commonly observed in cleft patients. More specifically, the prevalence of canine impaction in cleft patients is significantly higher compared with the general population, with a prevalence going up to 82 per cent in patients with UCLP (3–11), while in the general population, the frequency of occurrence ranges from 0.9 to 2.2 per cent (12–15). This difference in prevalence could be explained by the individual characteristics of the cleft, agenesis, and supernumerary teeth in the cleft region and the surgical procedures conducted in that area (1). In patients with UCLP, an alveolar bone graft is indispensable. The aim of this graft is to close the oronasal communication and to create a bony environment for the canine to erupt. The preferred moment to perform an alveolar bone graft is before maxillary canine eruption when the canine root development is one-fourth to a half (4). Ideally, the bone graft should be performed in combination with maxillary expansion before eruption of the canine to create a larger bony area and to decrease the impaction risk (7, 16–19). Up until now, iliac crest cancellous bone is still considered the ‘gold standard’ donor material (20). Canine impaction complicates the orthodontic treatment and may have deleterious effects on the adjacent teeth. Early diagnosis of canine impaction is crucial, and therefore, it is important to identify potentially predisposing factors. The aim of this study is to compare cleft-related impacted canine parameters with the normal contralateral side and with cleft-related non-impacted canine parameters in UCLP patients and to search for associated parameters of canine impaction at the cleft side that could possibly predict impaction. Materials and methods The Medical Ethics Committee of the University Hospitals Leuven registered and approved this study with the registration number S58229. Patient selection The present study sample consisted of non-syndromic UCLP patients who underwent secondary alveolar bone grafting between September 1997 and September 2016. All included patients were treated in the University Hospitals of Leuven, according to the same protocol, where lip closure is performed at the age of 3 months, the soft palate at approximately 12–18 months of age, and the hard palate at 4–6 years of age. The timing of the bone graft depends on the eruption of the canine and the position of the lateral incisor. It is most frequently performed around the age of 9, to allow eruption of the maxillary canine in a bony area. When the lateral incisor is located in the small segment, the bone graft is performed earlier. Two hundred and fifty-seven patients underwent secondary alveolar bone grafting between September 1997 and September 2016. Patients were excluded from the study when they had bilateral clefts (n = 60), unilateral cleft lip, and alveolus (n = 35), incomplete lip or palatal clefts (n = 13), clefts in the context of a syndrome (n = 9), when they were not surgically treated according to our protocol (n = 9), had their orthodontic treatment elsewhere (n = 5), when the maxillary canine was not erupted at the time of evaluation (n = 28), and when the patients had incomplete files (n = 3). The final sample consisted of 95 non-syndromic UCLP patients (65 males and 30 females, 31 cleft right side and 64 left side). The patients were divided into two groups according to their maxillary canine eruption. Group A included 41 patients with unilateral impacted canines at the cleft side (group A1) and spontaneously erupted canines at the non-cleft side (group A2). Group B included 54 patients with spontaneously erupted canines at both the cleft (group B) and non-cleft side (not used in the present study). Canines were considered as impacted according to the definition of Thilander and Jakobsson: ‘An impacted tooth is a tooth whose eruption is considerably delayed and for which there is clinical or radiographic evidence that further eruption may not take place’ (21). The canine needed to meet the following objective criteria to be classified as impacted and to be surgically exposed: the contralateral canine was erupted, the apex of the suspected canine was already closed, and the bone grafting procedure was performed more than 18 months ago. Data collection methods We collected the following parameters from the patient’s clinical records: gender, date of birth, date of secondary alveolar bone grafting, date of surgical exposure of the canine, presence of a crossbite, history of interceptive treatment, type of occlusion, and cleft side. Evaluation of radiographic parameters was performed on panoramic radiographs (OPG) before surgical exposure of the canine in group A and after the secondary bone graft where the root development of the canine was at least two-thirds in group B. The used parameters are explained in Table 1 and Figure 1. Table 1. Description of categorical and continuous variables. Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Canine development was scored according to the grading system of Ericson and Kurol (22); vertical position was scored using a modification on the method of Power and Short (23) (the central incisor was used when the lateral incisor was absent); for sector score, a modification on the method of Ericson and Kurol (22) was used (the central incisor was used when the lateral incisor was absent). View Large Table 1. Description of categorical and continuous variables. Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Parameters Description Scoring Categorical variables Occlusion [1] Angle Class III [2] Angle Class I [3] Angle Class II Canine development [1] Fully formed root [2] Root is longer than crown [3] Root is shorter than crown Canine apex [1] Open [2] Closed Deciduous canine [0] Absent [1] Present [2] Abnormal Permanent lateral incisor [0] Absent [1] Present [2] Abnormal Canine position [1] Palatal [2] Line of the arch [3] Buccal Resorption lateral incisor [1] Yes [2] No Vertical position of canine [1] Incisal to the cemento-enamel junction of the lateral incisor [2] Apical to the cemento-enamel junction but less than one-third of the root [3] More than one-third of the root but less than two-thirds [4] More than two-thirds of the root but incisal to the root apex [5] Above the root apex Sector score [0] Normal position of the canine [1] Distal to the long axis of the lateral incisor [2] Mesial to the long axis of the lateral incisor [3] Distal to the long axis of the central incisor [4] Mesial to the long axis of the central incisor Continuous variables Angle maxillary canine-midline 0–90° Angle maxillary canine-lateral incisor 0–90° Angle maxillary canine-first premolar 0–90° Canine development was scored according to the grading system of Ericson and Kurol (22); vertical position was scored using a modification on the method of Power and Short (23) (the central incisor was used when the lateral incisor was absent); for sector score, a modification on the method of Ericson and Kurol (22) was used (the central incisor was used when the lateral incisor was absent). View Large Figure 1. View largeDownload slide OPGs illustrating (a) vertical position of the canine (23), (b) sector of the canine (22), (c) angular measurements with (A) angle of maxillary canine to midline (= line through the inter-incisal point, perpendicular on the bottom of the OPG), (B) angle of maxillary canine to lateral incisor (the central incisor was used when the lateral incisor was absent), and (C) angle of maxillary canine to first premolar. Figure 1. View largeDownload slide OPGs illustrating (a) vertical position of the canine (23), (b) sector of the canine (22), (c) angular measurements with (A) angle of maxillary canine to midline (= line through the inter-incisal point, perpendicular on the bottom of the OPG), (B) angle of maxillary canine to lateral incisor (the central incisor was used when the lateral incisor was absent), and (C) angle of maxillary canine to first premolar. The OPGs were generated by a Siemens Orthopantomograph (Sirona Dental, Bensheim, Germany), a Cranex Tome (Soredex, Tuusula, Finland), a Veraviewpocs 2D (J. Morita Co., Kyoto, Japan), a VistaPano (Dürr Dental, Bietigheim-Bissingen, Germany), or a Promax 2D (Planmeca Inc., Helsinki, Finland). Statistical analysis Comparisons between group A1 and A2 were obtained by means of a generalized linear mixed model for binomial responses with a logit link and patient as a random factor. Comparisons between group A1 and B were obtained by means of a generalized linear model for binomial responses with a logit link. Model coefficients and their variance–covariance matrix were used to calculate the differences between the two groups. Continuous variables were compared between group A1 and B using a Mann–Whitney U-test. Non-continuous variables were compared between the same groups using a Fisher’s exact test. Receiver operating characteristic (ROC) curves were calculated to create threshold values for canine impaction (group A1 versus group B). For 20 randomly selected patients, the measurements were repeated after 1 month by the same observer and by a second observer. Rater agreements for categorical variables were assessed by means of a Fleiss’s Kappa statistic and for continuous variables by means of an intra-class correlation coefficient (ICC). P-values were only rated significant if they were smaller than 0.05. Results The descriptive data of the sample have been summarized in Table 2. Table 2. Descriptive data of the study sample. Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 View Large Table 2. Descriptive data of the study sample. Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 Study variable Group A Group B Patients with unilateral cleft lip and palate 41 54 Male:female ratio 33:8 32:22 Cleft right:left ratio 13:28 18:36 Age at bone graft (mean, range) 9.71 (7.19–11.74) 9.94 (7.38–17.21) Age at OPG (mean, range) 12.67 (9.9–15.5) 11.58 (8.4–16.9) Patients who had a crossbite before bone graft 33 46 Patients who had an interceptive treatment before bone graft 31 44 View Large Comparison of the impacted canine at the cleft side (A1) versus the spontaneously erupted canine at the non-cleft side (A2) In group A1, the patients had significantly more Class II malocclusion (P = 0.0043), while in group A2, they had significantly more Class III malocclusion (P = 0.0318). The canines at the non-cleft side were more developed than at the cleft side. The lateral incisor was often missing (41.5 per cent) or abnormal (46.3 per cent) at the cleft side. The vertical position of the maxillary canine was significantly higher at the cleft side versus the non-cleft side. At the non-cleft side, the canine was significantly more in the line of the arch in comparison with the cleft side. The canines at the non-cleft side had significantly more a sector score of 0. There was a significant difference between the angulations at both sides (P = 0.0001). The mean angle between the canine and the midline was 35.56 degrees at the cleft side and 5.34 degrees at the non-cleft side. The mean angle between the canine and the lateral incisor was 46.21 degrees at the cleft side and 7.93 degrees at the non-cleft side. The mean angle between the canine and the first premolar was 29.5 degrees at the cleft side and 5.91 degrees at the non-cleft side (Table 3 and Figure 2). Table 3. Comparison of categorical and continuous variables between groups A1, A2, and B (*P ≤ 0.05). Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* View Large Table 3. Comparison of categorical and continuous variables between groups A1, A2, and B (*P ≤ 0.05). Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* Parameters Study variable A1 A2 B A1 versus A2 (P value) A1 versus B (P value) Categorical variables (%) Occlusion  Class I 57.9 50 63 0.3224 0.6308  Class II 28.9 15.8 21.7 0.0043* 0.4487  Class III 13.2 34.2 15.2 0.0318* 0.7882 Canine development  Fully formed 43.9 65.9 31.5 0.0461* 0.215  Root is longer than crown 53.7 31.7 68.5 0.0448* 0.1404  Root is shorter than crown 2.4 2.4 0 0.9999 0.9859 Canine apex  Open 73.2 46.3 81.5 0.0135* 0.3357  Closed 26.8 53.7 18.5 0.0135* 0.3357 Deciduous canine  Present (no resorption) 7.3 0 1.9 0.9784 0.2051  Present (resorption) 2.4 22 7.4 0.0117* 0.2862  Absent 90.2 78 90.7 0.1322 0.9348 Permanent lateral incisor  Present 12.2 92.7 7.4 0.0001* 0.4332  Absent 41.5 2.4 42.6 0.0002* 0.9121  Abnormal 46.3 4.9 50 0.0001* 0.7238 Canine position  Palatal 41.5 0 22.2 0.9563 0.0451*  Buccal 9.8 17.1 1.9 0.1073 0.104  Line of arch 48.8 82.9 75.9 0.0013* 0.0067* Resorption lateral incisor  No resorption 80 100 92.6 0.9752 0.0755  Resorption 20 0 7.4 0.9752 0.0755 Vertical position of canine  1 2.4 85.4 42.6 0.0001* 0.0001*  2 48.8 9.8 50 0.0002* 0.9063  3 36.6 4.9 7.4 0.0001* 0.0007*  4 12.2 0 0 0.9769 0.9735 Sector score  0 22 95.1 50 0.0001* 0.0053*  1 22 4.9 27.8 0.0266* 0.5167  2 34.1 0 11.1 0.958 0.0074*  3 17.1 0 7.4 0.9758 0.1501  4 2.4 0 0 0.9877 0.9859 Continuous variables (mean angle) Angle canine-midline 35.56 5.34 18.92 0.0001* 0.0001* Angle canine-lateral incisor 46.21 7.93 28.39 0.0001* 0.0001* Angle canine-first premolar 29.5 5.91 13.14 0.0001* 0.0001* View Large Figure 2. View largeDownload slide Boxplots showing the difference in canine angulation with respect to (a) midline, (b) lateral incisor, and (c) first premolar between groups A1, A2, and B. Figure 2. View largeDownload slide Boxplots showing the difference in canine angulation with respect to (a) midline, (b) lateral incisor, and (c) first premolar between groups A1, A2, and B. Comparison cleft side with impaction (A1) versus cleft side without impaction (B) There were no significant differences in occlusion and in development of the canine between both groups. The lateral incisor was often missing or abnormal in both groups; no significant difference was noted. The vertical position of the maxillary canine was significantly higher in group A1 versus group B. In group B, the canine was significantly more in the line of the arch in comparison with group A1 (P = 0.007), where the canine was significantly more palatally located. The canines in group B had significantly more a sector score of 0. There was a significant difference between the three angles in group A1 versus group B (P = 0.0001). The mean angle between the canine and the midline was 35.56 degrees in group A1, while it was 18.92 degrees in group B. The mean angle between the canine and the lateral incisor was 46.21 degrees in group A1 and 28.39 degrees in group B. The mean angle between the canine and the first premolar was 29.5 degrees in group A1 and 13.14 degrees in group B (Table 3 and Figure 2). Impaction of the maxillary canine at the cleft side in UCLP patients can be suspected in case of delayed canine root development, a higher vertical position and sector score (P < 0.05) and higher angles between the canine and the midline, as well as between canine and lateral incisor and between first premolar (P < 0.001). It must be noted that the position of an erupting canine at the cleft side, even when not impacted, is different from the non-cleft side. The three angles are significantly larger, root development and eruption are slower, and canines have a more mesial position than those at the non-cleft side. ROC tests were performed to decide which continuous and ordinal parameters were the best-associated parameters of canine impaction at the cleft side. According to our measurements, the angulation between the canine and the midline was the best parameter, followed by the angulation between the canine and the first premolar, the vertical position of the canine, the angulation between the canine and the lateral incisor and the sector score. The area under the curve (AUC) for canine development was too low to have a clinically significant predictive value. Based on the aforementioned parameters, certain cut-off values were set to discriminate between impaction and non-impaction of the canine at the cleft side (Table 4). Table 4. Discrimination between impaction and non-impaction at the cleft side (A1 versus B). Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Angles are shown in degrees, vertical position, and sector score are shown as mentioned in Table 2. View Large Table 4. Discrimination between impaction and non-impaction at the cleft side (A1 versus B). Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Study variable Area under the curve Sensitivity (%) Specificity (%) Threshold value Angle canine to midline 0.83 81.6 73.3 23.82° Angle canine to first premolar 0.81 84.2 71.1 16.10° Vertical position of canine 0.80 50 93.3 >2 Angle canine to lateral incisor 0.73 71.1 73.3 40.22° Sector score 0.72 57.9 82.2 >1 Canine development 0.43 55.3 28.9 >1 Angles are shown in degrees, vertical position, and sector score are shown as mentioned in Table 2. View Large The Fleiss’s kappa value for the inter-observer agreement ranged from 0.60 to 0.94, except for resorption of the lateral incisor, for which it was 0.46. The Fleiss’s kappa value for the intra-observer agreement ranged from 0.75 to 1. The ICC was 0.95 or higher for both inter-observer and intra-observer agreement. Discussion Maxillary canine impaction is an important clinical manifestation, as it is frequently found in UCLP patients. In spite of this, it remains to be an understudied clinical feature. Early diagnosis of canine impaction is crucial to prevent resorption of adjacent teeth, and therefore, it would be valuable to identify potentially predisposing factors. There have been several attempts to predict canine impaction on OPGs in the general population, but in patients with UCLP, evidence is still lacking (24–28). In our sample, the patients in group A were significantly older than those in group B (12.67 years versus 11.58 years). As a consequence, the canines in group B should be less developed, should have a higher vertical position, and larger angles with the midline, lateral incisor, and first premolar. However, according to our results, there is no significant difference in canine development between group A and B, despite the fact that the patients in group B were significantly younger at the time of the OPG. As a consequence, if the patients in group B would have the same age as in group A, the differences would be even greater. El Deeb et al. (4) indicated that canines at the cleft side erupt slower than those at the contralateral side, and additionally, delayed root development may increase the risk of tooth impaction. Our results are consistent with these findings. Canines at the cleft side had a higher vertical position in comparison with canines at the non-cleft side, and impacted canines had a slower root development than spontaneously erupted canines. As mentioned in the Results section, patients with an impacted canine at the cleft side had significantly more often a Class II malocclusion than the same patients at the non-cleft side. This fact may be due to mesialization of the teeth at the cleft side, as a consequence of an absent or abnormal lateral incisor. Several authors state that impaction often coincides with an absent or abnormal lateral incisor (9, 19, 29), as the guidance theory indicates that the lateral incisor plays a significant role in guiding the maxillary canine to its correct position. Contradictory, other authors have found that lateral incisor agenesis does not modify the impaction risk (8, 30–32). In the present study, when group A1 (impacted canine at the cleft side) was compared with group B (spontaneously erupted canine at the cleft side), no significant differences between both groups were found for the presence of the lateral incisor. According to our findings, an absent or abnormal lateral incisor is more a characteristic of a cleft site than a predictor for impaction, which would support the idea that lateral incisor agenesis does not modify the impaction risk, as stated by the most recent literature (8, 32). Several authors have already suggested that certain parameters could be distinctive for canine impaction. Therefore, ROC tests were performed on the study variables to determine the best-associated parameters of canine impaction in patients with UCLP. First, the angle between the canine and the midline could have a predictive value for tooth impaction. Russel and McLeod stated that an angle greater than 45 degrees indicated risk of canine impaction (19), while Westerlund et al. (11) set the cut-off for this at an angle larger than 30 degrees and Ericson and Kurol (22) at an angle larger than 25 degrees. Nevertheless, in patients with UCLP, the mean angle between the maxillary canine and the midline at the cleft side is already significantly larger than at the non-cleft side, even when the canine is not impacted. Therefore, only the parameters of the canines at the cleft sides (group A1 versus group B) were compared to determine the cut-off values because the measured angles are not comparable with non-cleft sides. Based on this, the mean angle between the impacted canine and the midline was 35.56 degrees, and a cut-off value of 23.8 degrees was set in the present study. Warford et al. (28) stated that sector score is the most important predictor of eventual impaction. They also stated that angulation does not play a significant role in prediction of canine impaction. Ericson and Kurol (22) and Sajnani and King (27), on the contrary, describe angulation of the canine to the midline as a powerful prediction factor, as well as the angulation of the canine to the lateral incisor and the sector score. Alqerban et al. (25) found the angle between the canine and the first premolar to be a good discriminator for canine impaction. In the present study, statistically significant differences were noticed between the impacted canines and both control groups for the above-mentioned study variables, supporting the idea that these parameters are indeed good discriminators for impaction. However, the sector score and the angle between the canine and the lateral incisor may not be the most appropriate discriminators for canine impaction in patients with UCLP because the lateral incisor is often absent or abnormal, and other parameters should, in our opinion, be preferred. The ROC tests have indicated that the angle between the canine and the midline, the angle between the canine and the first premolar, and the vertical position of the canine are the three best-associated parameters of canine impaction with the cut-off values mentioned in Table 4. It is important to state that our estimation of the cut-off values was based on one OPG per patient, so they are most valid when the patients are around the age of 11–13 years old. The male:female ratio in patients with UCLP is 2:1, and the left side is significantly more affected than the right side (1, 33). The present study population follows this distribution. In the general population, girls also have twice as often impacted canines (34). However, we can’t make statements about the correlation gender and impaction in the present study population because of the size of the groups (Table 2). Most of our measurements were performed on OPGs. Although limitations of 2D images have been widely discussed in literature (distortion, magnification, superimposition, and positioning errors) (35), they remain to be of great clinical value because they are routinely taken at multiple moments throughout the patient’s treatment. Three-dimensional radiographs are exempt of this problem, but in CLP patients, they are already taken before and after the bone graft. Due to this, it not always justified to take an additional 3D radiograph only for canine impaction screening, with the extra radiation dose and costs that this implies. Additionally, several authors indicate that angular and linear measurements can be accurately performed on OPGs (25, 27, 35). In the present study, the kappa values and the ICC were acceptable, except for resorption of the lateral incisor, which showed a kappa value of 0.46. This implies that resorption is not consistently measurable on OPGs. To know the exact position of the canine and to evaluate the exact amount of resorption of the adjacent teeth, 3D images remain to be the ideal radiographic projection. It is important to notice that the present study has some limitations regarding the study design. It is a retrospective cross-sectional study which means that it has less power than a prospective study to support the outcomes mentioned in the Results section. Ideally, the associated parameters of canine impaction should be studied in a prospective setting to confirm their predictive value. Additionally, a split-mouth design was used in the present study, which may not be the best option in patients with UCLP because of the aforementioned genetic, environmental, and local factors. Two control groups were used: one where the impacted canine at the cleft side (group A1) was compared with a non-impacted canine at the non-cleft side (group A2) and another UCLP control group where the non-impacted canine at the cleft side (group B) was used. Ideally, non-cleft patients without tooth impaction should be used as a control group. As it often happens with comparative studies regarding conditions with low prevalence as cleft lip and palate, the groups included a small number of patients, and a cross-sectional retrospective design had to be used. Prospective longitudinal multicenter studies with large sample sizes and good control groups should be encouraged to validate the predictive value of the parameters found in the present study and to draw further conclusions. Despite these limitations, determining associated parameters of canine impaction in UCLP patients still has a clear clinical value. Up until now, the decision to intervene the maxillary canine eruption in these patients has been most frequently based on subjective factors. In the present study, cut-off values for several parameters with an adequate AUC were statistically determined, in order to be able to distinguish between impaction and non-impaction at the cleft side. This contrasts other articles studying patients with cleft lip and palate taking only one distinctive parameter into account or with non-statistically supported cut-off values (11, 19). We believe that our parameters can help the practitioner to make a more objective and scientifically based decision and can pave the way for further research. However, these parameters remain to be a diagnostic tool, and each patient should be evaluated on an individual level. Conclusion Careful follow-up of maxillary canines is crucial in patients with UCLP. OPGs are useful to evaluate the eruption path of the maxillary canines, while root resorption and canine position are ideally evaluated in 3D images. In the present study, the three best-associated parameters of canine impaction at the cleft side are a vertical position more apical than one-third of the root of the lateral incisor and the angles between canine and midline and between canine and first premolar larger than 23.82 and 16.1 degrees, respectively. These parameters represent a valuable tool to help the practitioner in their decision to intervene when they suspect an impacted canine in UCLP patients. However, they should be studied in a prospective setting to confirm their predictive value. Conflict of Interest None to declare. References 1. Dewinter , G. , Quirynen , M. , Heidbüchel , K. , Verdonck , A. , Willems , G. and Carels , C . 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The European Journal of OrthodonticsOxford University Press

Published: Mar 21, 2018

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